Craig Lawrance

Technical Manager, Textile Centre of Excellence

craiglawrance@textile-training.com

New Sustainable Chemistry

4th April 20173rd Thematic Presentation, Bucharest

2

Sustainability Challenges of the

Textile & Dyeing Industries –

opportunities for innovation

3

Necessity for

Sustainable Products

2012 - world population 7 billion

2050 - expected to rise to over 9 billion

Increases demand

food, energy, water, resources, chemicals

Increases environmental burden

pollution

depletion of finite non-renewableresources (e.g. fossil fuels)

4

Definition of Sustainability

E

N

V

I

R

O

N

M

E

N

T

S

O

C

I

E

T

Y

E

C

O

N

O

M

Y

5

Sustainability considerations

WATER EMISSIONS

ENERGYRAW

MATERIALS

6

Ideal sustainable product

Provide an equivalent function to the product it replaces

Performs as well as or better than the existing product

Be available at a competitive or lower price

Have a minimum environmental footprint for all the processes involved

Be manufactured from renewable resources

Use only ingredients that are safe to both humans and the environment

No negative impact on food supply or water

7

Textile dyeing processes

Traditional dyeing processes use 5.8 trillion

litres water p.a.~3.7 billion Olympic swimming pools

10-20% dye remains after dyeing (plus other

chemicals), leaving potential for wastewater

pollution

One fifth of the world's industrial water

pollution (World Bank)

391 billion kWh energy for dyeing processes

Innovative technologies needed to reduce, or

eliminate, water, energy and auxiliary

chemicals in dyeing

8

Treatment of textile

dyeing effluent

Wastewater discharged from dyeing processes one of

biggest contributors to textile effluent

Mainly residual dyes and auxiliary chemicals

>50,000 tpa dye discharged into effluent

Dye Class Fibre Loss to effluent (% applied)

acid polyamide 5-20

basic acrylic 0-5

direct cotton 5-30

disperse polyester 0-10

metal-complex wool/polyamide 2-10

reactive cotton 10-50

sulphur cotton 10-40

vat cotton 5-20

9

Treatment of textile

dyeing effluent

Dyeing effluent in a watercourse aesthetically

undesirable, but has a more serious

environmental impact

High BOD combined with spectral absorption of

dye

Can affect photosynthetic processes

Reduction in O2 levels in the water →

suffocation of aquatic flora and fauna

Dyestuffs may be also have aquatic toxicity

(metals, AOX)

Several methods developed to remove colour

from dyehouse effluent

Varying in effectiveness, economic cost, and

environmental impact (of the treatment process

itself)

Blackburn RS, Environ. Sci. Technol. 2004, 38, 4905.

10

Coloration of cotton

Dyeing of cotton primarily conducted using reactive dyes

Despite development of dyes with high fixation, dyeing still uses high

quantities of salt, water (and energy), and creates colour pollution

• Soil too alkaline to

support crops

• Kills aquatic life

• Fresh watercourses

turned saline

downstream from

dyehouses

• Difficult to remove

from effluent

• 10-40% dyestuff hydrolysed• Goes down drain• Aesthetically unpleasant• Blocks sunlight• Kills aquatic life

• Clean effluent• High cost

• High level in dyeing• Incredible volume in

wash-off• Up to 10 separate

rinsings• High energy

consumption• 50% total cost

dyeing procedure

11

Traditional Reactive Dyeing Process

1st Stage of Reactive Dyeing

• dye absorbs onto cellulose substrate through hydrogen bonding in aqueous

solutions with a high level of electrolyte addition

• dye adsorption onto the fibre is enabled, higher salt leads to better dye uptake

2nd Stage of Reactive Dyeing

• addition of alkali to achieve pH 11 generates covalent bonding between dye and

fibre

• however, alkaline environment produces hydroxyl ions in solution which react with

the dye to create hydrolysed dye (as much as 40% of the dyestuff may be

hydrolysed)

• whilst the hydrolysed dyes have an affinity for the fibre, it is not covalently bonded

12

Traditional Reactive Dyeing Process

Wash-off of Reactive Dyeings

• reactive dyeings require a multistage wash-off process after dyeing involving

various aqueous rinses and washing to remove hydrolysed dye and achieve the

characteristic high colour fastness

• wash off and subsequent effluent treatment can account for up to 50% of the total

cost of reactive dyeing

• high levels of electrolyte causes dye molecules to aggregate making the

hydrolysed molecules difficult to remove

• several wash off processes are needed, the first 2 are mainly to dilute the

electrolyte levels, subsequent stages remove the hydrolysed dye from the

substrate to achieve the high colour fastness required

• the wash off process uses large volumes of water, high energy levels to raise the

water temperature for efficient washing as well as increasing greatly the time taken

for dyeing and reducing productivity

13

Use of Dye Transfer Inhibitors (DTI)

Novel DTI Wash-off Process

• water and energy are the biggest issues in dyeing of textiles

• DTIs have long been used in domestic laundry detergents for holding soils and dye

molecules in suspension and preventing re-deposition onto the textile

• existing and developmental DTIs were used to remove unfixed hydrolysed dyes

following the reactive dyeing of cotton

• the objective was to drastically reduce the wash off procedure, reduce energy,

time, cost and gain a substantial sustainability benefit

14

The ProcessRecommended Dyeing and Wash-

off Method

• Fabric, reactive dye and sodium

sulphate added to water (10:1

solution to fibre ratio), held at 50 °C

for 20 min, temp raised 1.5 °C/min to

80 °C and held for 30 min.

• Sodium carbonate added to change

pH to 10.5 and held at 80 °C for 60

min. Fabric then removed.

• Fabric washed-off according to Dye

Manufacturer instructions using

6-stage process.

Recommended Dyeing Method and

DTI Wash-off Process

• Fabric, reactive dye and sodium

sulphate added to water (10:1 solution

to fibre ratio), held at 50 °C for 20 min,

temp raised 1.5 °C/min to 80 °C and

held for 30 min.

• Sodium carbonate added to change pH

to 10.5 and held at 80 °C for 60 min.

Fabric then removed.

• Fabric washed off in a 3-stage process

i. washed in water (10:1 solution to fibre ratio)

at 20 °C for 10 min. Wash bath then

emptied

ii. DTI and water added (10:1 solution to fibre

ratio) at 40 °C for 10 min. Wash bath then

emptied

iii. washed in water (10:1 solution to fibre ratio)

at 20 °C for 10 min. Wash bath then

emptied

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Comparison of the two processes

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360

Time (min)

Tem

pera

ture

(d

eg

rees C

)

10:1 LR

dyed fabric

10:1 LR

dyed fabric

10:1 LR

dyed fabric

10:1 LR; dyed fabric

1.0 g/l non-ionic

detergent OR

0.5 g/l sequestrant 10:1 LR; dyed fabric

10:1 LR; dyed fabric

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360

Time (min)

Tem

pera

ture

(d

eg

rees C

)

10:1 LR; dyed fabric; 1.0 g/l DTI agent

10:1 LR; dyed fabric

10:1 LR; dyed fabric

Traditional methodology Use of DTIs

16

Wash-off of reactive

dyeings on cotton

• Dye transfer inhibiting (DTI) polymers (used in laundry

detergents) were employed to remove unfixed dyes

• Much more efficient, economical and sustainable

process developed

• Significantly reduces operation time, water

consumption and energy consumption

• poly(vinylpyridine-N-oxide) polymers were the most effective

• poly(vinylpyridine betaine) polymers also highly efficient

Procedure Time

(min)

Water

(L/kg

fabric)

Energy

(MJ/kg fabric)

Recommended

wash-off

250 60 9.21

DTI wash-off 50 30 0.84

Amin MN, Blackburn RS, ACS Sus. Chem. Eng. 2015, 3, 725.

17

Grey Scale Rating for Staining to Adjacent Cotton

DTI C.I. Reactive Red 120 C.I. Reactive Yellow 84 C.I. Reactive Red 141 C.I. Reactive Blue 171

20 g dm-3

Na2SO4

No Na2SO4 20 g dm-3

Na2SO4

No Na2SO4 20 g dm-3

Na2SO4

No Na2SO4 20 g dm-3

Na2SO4

No Na2SO4

None 2/3 3 2 3 2 3 2/3 3

Sandozin NIE 3/4 4 3/4 4 3 4 3/4 4

PVP 4/5 4/5 4 4/5 4/5 4/5 4/5 4/5

PVP K-15 4/5 5 4 4/5 4/5 4/5 4/5 4/5

PVP K-30 4/5 4/5 4/5 4/5 3/4 4 4 4

PVP K-90 4/5 4/5 4/5 4/5 4 4 4 4

PVP K-120 5 5 4/5 4/5 4 4/5 4 4/5

Chromabond S-100 5 5 5 4/5 4/5 4/5 4/5 4/5

Chromabond S-403E 5 5 5 5 5 5 5 5

PVNO Classic 5 5 5 5 5 5 5 5

PVNO Europe 5 5 5 5 4/5 5 5 5

Standard wash-off 5 5 5 5 5 5 5 5

Project smedia

Thank you!

Questions welcome